The present invention relates to data protection and more particularly to emulating commands that are implemented by physical tape libraries (PTLs) to facilitate communication and data movement between a PTL and data protection applications (DPAs). The commands are emulated so that backup data may be copied from DPAs to disk-based virtual tape libraries (VTLs) without requiring the DPA to support disk as a backup medium. In other words, a tape library interface is added to a standard disk array.
Data protection (which includes backing up computer data, restoring computer data, securing computer data, and managing computer data storage) and disaster recovery procedures are essential processes to organizations that use computers. In fact, data protection is the single most expensive storage administrative task. Most large organizations perform data backups to tape media and use a robotically-controlled tape library or tape jukebox to assist with backup automation. Performing and managing backups and restores involves many functions including, for example, media management (including tape tracking, rotation and off-site storage), tape jukebox management, file tracking, backup scheduling, assisted or automated data restore and data archival.
In order to effectively perform the above functions, a sophisticated DPA is required. Examples of such DPAs include, for example, Legato NetWorker, Veritas BackupExec and CA ArcServe. DPAs automate and assist with the essential functions of data protection.
DPAs are designed specifically to work with physical tapes, tape drives and PTLs. In fact, most of the complexities in DPAs relate to their interaction with those physical devices. Unfortunately, physical tape devices tend to be slow and error prone: tape robots fail, tape drives misbehave, tape media wears out or tears, etc. It would therefore be preferable to backup data to disk arrays, which are less error prone and perform better. Advanced Technology Attachment (ATA) disk drives have also reached price parity with tape media, which adds a large incentive to move from tape-based solutions to disk-based solutions. However, existing DPAs were designed to work with physical tape libraries and they encounter numerous difficulties when dealing with disk arrays.
It would therefore be desirable to add a tape library emulation layer to disk arrays that allows DPAs to read and write to disk arrays in the same fashion they read and write to tape.